It is well known to employ fluorocarbons as propellants in dispensing fluids under pressure in container-like structures. However, recent environmental concern regarding the use of fluorocarbons and their potentially harmful effects on the ozone layers of the upper atmosphere has prompted a search for a replacement of such fluorocarbons. One such replacement includes the use of hydrocarbons which, however, have undesirable after effects and inherent dangers as well. In particular, hydrocarbons provide a flammable medium which in itself presents the danger of explosion and/or fire. Moreover, the use of propellants requires that the containers be constructed of sufficient strength so as to preserve and maintain the pressures generated within such containers. As a result, the use of such propellants provides an ever-present inherently dangerous situation in that rough handling or puncturing of the outer containers at any time can cause explosions.
Accordingly, attempts to avoid the use of propellants such as fluorocarbons or hydrocarbons have included resorting to the use of mechanical pump systems. Such pump devices disadvantageously require constant manual manipulations or pumping simply to provide release and dispersal of the fluid from the container as is typically obtained by propellant devices as noted above.
In view of the above-noted deficiencies of prior art systems, devices have been developed which incorporate an elastomeric member as described and illustrated in U.S. Pat. Nos. 3,672,543 and 3,738,538 to Roper et al.; U.S. Pat. Nos. 3,791,557 and 3,796,356 to Venus, Jr.; U.S. Pat. No. 3,876,115 to Venus, Jr. et al. and U.S. Pat. No. 3,961,725 to Clark. In the above-noted patents an elastomeric container serves to contain a fluid and is positioned within a housing whose shape the elastomeric container is intended to assume upon expansion. A valve structure positioned atop the housing communicates with the fluid within the elastomeric container. Upon activation of the valve structure, the fluid is expelled by means of the force exerted by the contraction of the elastomeric container to an unexpanded state. Furthermore, each of the patents noted above incorporates a mandrel which is positioned centrally of the elastomeric container and provides for prestressing of the container and/or evacuation of the fluid along channels or grooves along the length of the mandrel.
Such prior art devices, however, inherently suffer from the problem of odor contamination of the fluid by the rubber composition of the container. Moreover, in these devices filling the container often results in unregulated expansion. For this reason, the container can expand into various shapes and in certain instances the container expands into contact with the inner surface of the housing prior to achieving full expansion within the housing. As a result, portions of the container are subjected to frictional forces during expansion. This in turn produces wear and tear in the container structure which may thereafter operate erratically, i.e., not produce constant expression of fluid throughout the range of evacuation of the container upon activation of the valve structure. In some instances, the container may become damaged and even rendered inoperative.
In an attempt to overcome the first of the abovementioned deficiencies, U.S. Pat. No. 4,121,737 to Kain discloses an apparatus having a pressure container of suitable elastomeric material such as rubber which envelops a flexible fluid-tight bag or liner. Such liner is provided in order to prevent the fluid from contacting the elastomeric material of the pressure unit and thus to avoid acquiring undesirable odors or flavors. However, as is the case with the other patents noted above, the device of the Kain patent does not provide control or regulation for the expansion of the pressure container. Accordingly, the container expands within the housing in an uncontrolled fashion and often contacts the inner walls of the housing during its expansion. Thus, the device of the Kain patent does not avoid the distortion disadvantages and operational limitations resulting therefrom as noted above.
In addition, in known devices which employ a liner within an elastomeric container, the liner is generally of a uniform construction which does not permit easy folding about a given axis. Rather, as is the case with the device of the Kain patent, the liner is crumpled within the elastomeric container prior to being filled with a fluid. Moreover, the known liners constructed of a material of uniform thickness throughout have been known to undergo blowouts during the filling process during which greater pressures are exerted against certain portions of the liner. Blowouts have also been known to occur in liners constructed as enclosed containers and sealed in position within an outer housing. In such instances the seals themselves may weaken and rupture during filling or use. I have invented an apparatus and a method of manufacturing an apparatus for containing and dispensing fluids under pressure which overcomes the above-noted limitations of the prior art.